Evaluation of a Seismic Pavement Analyzer for Pavement Condition Monitoring

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CAIT project no.: FHWA NJ 2002 012

Fiscal Year: 1996/1997

Status: Final

Rutgers-CAIT Author(s): Nenad Gucunski, Ali Maher

External Author(s): Nicholas Vitillo



Seismic Pavement Analyzer (SPA) is a device for nondestructive evaluation of pavements developed under the Strategic Highway Research Program (SHRP). One of the main objectives in the development of the SPA was to create a device that will allow measurement of onset of deterioration at early stages, and thus contribute to a more economic pavement management. Primary applications of the SPA include pavement profiling in terms of elastic moduli and layer thicknesses, detection of voids or loss of support under rigid pavements, delamination in rigid pavements and bridge decks, and subgrade evaluation. The SPA incorporates five seismic techniques for those purposes: Ultrasonic Body-Wave (UBW), Ultrasonic Surface-Wave (USW), Impact Echo (IE), Impulse Response (IR) and Spectral Analysis of Surface Waves (SASW). The SPA was evaluated for possible implementation in evaluation and condition monitoring of pavements in New Jersey. Specifically, the objectives of the study were to examine the applicability of the SPA in pavement structural evaluation, detection of defects and distresses, and other uses relevant for pavement evaluation and condition monitoring. With respect to the equipment itself, the objectives were to examine the robustness and consistency of the SPA hardware and software, and the soundness of the seismic methods implemented in the device. To achieve the objectives of the study, a number of flexible and rigid pavements in New Jersey were tested. Specific attention was given to pavement profiling and detection of voids or loss of support under rigid pavements. Use of the SPA in evaluation of joint load transfer in rigid pavements was examined too. The overall conclusion of the study is that the SPA is a well designed automated data collection and analysis system for seismic testing of pavements. The five seismic techniques implemented in the SPA utilize sound physical phenomena of wave propagation in layered elastic systems. However, several data interpretation procedures, in particular those related to SASW and IR, have significant space for improvement. The strongest capability of the SPA is in evaluation of the properties of the paving layer, since those are being directly measured. The SPA hardware performed very well throughout the study, with minimum failures and simple and inexpensive regular maintenance. However, transition from DOS to Windows platform is necessary to improve capabilities, versatility and user-friendliness of the SPA software. Benefits of the SPA can be significantly improved through both continued fundamental research and a number of short analytical and experimental studies. The most of the effort should be directed towards the improvement of the analytical procedures, in particular of the SASW and IR methods. Minor improvements on the hardware side should lead to significant enhancement of ultrasonic techniques. Other potential applications of the SPA still need to be examined or verified, like: the use of SPA in detection and characterization of delaminations in rigid and composite pavements, evaluation of temperature induced modulus variations in asphalt concrete, or monitoring of curing of concrete.